Ceramic oxygen transport membrane array reactor and reforming method

ABSTRACT

A commercially viable modular ceramic oxygen transport membrane reforming reactor for producing a synthesis gas that improves the thermal coupling of reactively-driven oxygen transport membrane tubes and catalyst reforming tubes required to efficiently and effectively produce synthesis gas.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application Ser. Nos. 61/887,751, filed Oct. 7, 2013; 61/932,974,filed Jan. 29, 2014; and 61/985,838, filed Apr. 29, 2014, thedisclosures of which are incorporated by reference herein.

STATEMENT OF GOVERNMENT RIGHTS

This invention was made with Government support under CooperativeAgreement No. DE-FC26-07NT43088, awarded by the United States Departmentof Energy. The Government has certain rights in this invention.

FIELD OF THE INVENTION

The present invention provides a method and apparatus for producing asynthesis gas from a hydrocarbon containing gaseous feed introduced intoan oxygen transport membrane based reforming reactor comprised of anarray of ceramic oxygen transport membrane tubes and catalyst containingreforming tubes. More particularly, the present invention provides amodular based oxygen transport membrane based reforming reactor that hasa high degree of thermal coupling and packing density to optimize thesynthesis gas production per unit volume of the reactor.

BACKGROUND OF THE INVENTION

Synthesis gas containing hydrogen and carbon monoxide is produced for avariety of industrial applications, for example, the production ofhydrogen, chemicals and synthetic fuel production. Conventionally, thesynthesis gas is produced in a fired reformer in which natural gas andsteam is reformed in nickel catalyst containing reformer tubes at hightemperatures (900 to 1,000° C.) and moderate pressures (16 to 20 bar) toproduce the synthesis gas. The endothermic heating requirements forsteam methane reforming reactions occurring within the reformer tubesare provided by burners firing into the furnace that are fueled by partof the natural gas. In order to increase the hydrogen content of thesynthesis gas produced by the steam methane reforming (SMR) process, thesynthesis gas can be subjected to water-gas shift reactions to reactresidual steam in the synthesis gas with the carbon monoxide.

A well-established alternative to steam methane reforming is the partialoxidation process (POx) whereby a limited amount of oxygen is allowed toburn with the natural gas feed creating steam and carbon dioxide at hightemperatures and the high temperature steam and carbon dioxide aresubjected to subsequent reforming reactions.

A key shortcoming of both the SMR and POx processes is the significantamount of carbon emitted to the atmosphere as carbon dioxide gas in thelow-pressure flue gas. In addition, producing synthesis gas byconventional SMR or POx processes are recognized to be a relativelyexpensive processes.

An attractive alternative process for producing synthesis gas is anoxygen-fired autothermal reformer (ATR) process that uses oxygen topartially oxidize natural gas internally in a reactor which retainsnearly all the carbon in the high pressure synthesis gas, thusfacilitating removal of carbon dioxide for carbon capture. However, theATR process requires a separate air separation unit (ASU) to producehigh purity, high-pressure oxygen, which adds complexity as well ascapital and operating cost to the overall process.

As can be appreciated, the conventional methods of producing a synthesisgas such as SMR, POx or ATR systems are expensive and require complexinstallations. In order to overcome the complexity and expense of suchinstallations it has been proposed to generate the synthesis gas withinreactors that utilize an oxygen transport membrane to supply oxygen andthereby generate the heat necessary to support endothermic heatingrequirements of the steam methane reforming reactions. A typical oxygentransport membrane has a dense layer that, while being impervious to airor other oxygen containing gas, will transport oxygen ions whensubjected to an elevated operational temperature and a difference inoxygen partial pressure across the membrane.

Examples of oxygen transport membrane based reforming reactors used inthe production of synthesis gas can be found in U.S. Pat. Nos.6,048,472; 6,110,979; 6,114,400; 6,296,686; 7,261,751; 8,262,755; and8,419,827. The problem with all of these oxygen transport membrane basedsystems is that because such oxygen transport membranes need to operateat high temperatures of around 900° C. to 1100° C., preheating of thehydrocarbon feed to similarly high temperatures is often required. Wherehydrocarbons such as methane and higher order hydrocarbons are subjectedto such high temperatures, excessive carbon formation will occur in thefeed stream, especially at high pressures and low steam to carbonratios. The carbon formation problems are particularly severe in theabove-identified prior art oxygen transport membrane based systems. Adifferent approach to using an oxygen transport membrane based reformingreactor in the production of synthesis gas is disclosed in U.S. Pat. No.8,349,214 and United States Patent Application Serial No. 2013/0009102both of which disclose a reactively driven oxygen transport membranebased reforming system that uses hydrogen and carbon monoxide as part ofthe reactant gas feed which address many of the highlighted problemswith the earlier oxygen transport membrane systems. Other problems thatarise with the prior art oxygen transport membrane based reformingsystems are the cost and complexity of the oxygen transport membranemodules and the lower than desired thermal coupling, durability,reliability and operating availability of such oxygen transport membranebased reforming systems. These problems are the primary reasons thatoxygen transport membranes based reforming systems have not beensuccessfully commercialized. Recent advances in oxygen transportmembrane materials have addressed problems associated with oxygen flux,membrane degradation and creep life, but there is much work left to bedone to achieve commercially viable oxygen transport membrane basedreforming systems from a cost standpoint as well as from an operatingreliability and availability standpoint.

Process designs that utilize thermally coupled separate oxygen transportmembrane and catalytic reforming reactors have their own set ofchallenges. For example, oxygen transport membranes may be configured toperform several tasks such as separation of oxygen from air, reaction ofpermeated oxygen with a reactant stream to produce a water vaporcontaining reactant stream required to support endothermic reactions inthe catalytic reforming reactor and transferring heat to drive theendothermic reactions in the catalytic reforming reactor to achievedesired production of synthesis gas. Heat to support endothermicreactions within catalytic reactors is mostly provided by radiant heattransfer of the heat released from combustion of permeated oxygen in theoxygen transport membrane reactor. At elevated temperatures the oxygentransport membranes are subjected to considerable mechanical stressesboth during normal steady-state operation and transient operations suchas start-up, shutdown, as well as, upset conditions, particularly atdetrimental levels when temperatures or rate of temperature change maybe outside acceptable ranges. Thus, inefficient transfer of exothermicheat released in the oxygen transport membrane reactors to the catalyticreforming reactors will lead to less efficient operation, higher capitalcost and more complex system.

The need, therefore, continues to exist for a synthesis gas generationsystem that has a high degree of thermal integration efficiency, higherheat transfer surface areas, and high packing density to optimize thesynthesis gas production per unit volume of the reactor. The presentinvention addresses the aforementioned problems by providing acommercially viable modular ceramic oxygen transport membrane assemblythat improves the maintainability and manufacturability of the synthesisgas production system and, more importantly, improves the thermalcoupling of the reactively-driven oxygen transport membrane tubes andcatalyst reforming tubes required to efficiently and effectively producesynthesis gas.

SUMMARY OF THE INVENTION

The present invention in one or more aspects can be characterized as anoxygen transport membrane panel for transferring radiant heat to aplurality of catalytic reforming reactors, the oxygen transport membranepanel comprising a panel frame or support structure and a plurality ofoxygen transport membrane repeating units within or attached to thepanel frame wherein the oxygen transport membrane repeating units arearranged in a tightly packed linear or co-planar orientation. Eachoxygen transport membrane repeating unit comprises two or more oxygentransport membrane tubes coupled together at one end to form amulti-pass arrangement and the other end of the tubes configured to bein fluid communication with either a feed manifold or an exhaustmanifold. In addition, each oxygen transport membrane tube has apermeate side located on an interior surface of the tube and a retentateside located on an exterior surface of the tube.

The oxygen transport membrane panels are configured to separate oxygenfrom an oxygen containing stream contacting the retentate side of thetubes in cross-flow arrangement and react the permeated oxygen with agas stream containing hydrogen and carbon containing species introducedinto the permeate side of the tubes thereby producing radiant heat and asteam containing reaction product stream. The catalytic reformingreactors placed in a juxtaposed relationship, and more preferably aparallel or substantially parallel orientation, with respect to theoxygen transport membranes. The catalytic reforming reactors areconfigured to produce synthesis gas from in the presence of the radiantheat and a hydrocarbon containing reactant stream containing thereaction product stream from the oxygen transport membrane panels. Theview factor between the oxygen transport membrane panels radiating heatto the catalytic reforming reactors is preferably greater than or equalto about 0.4 whereas the surface area ratio between the catalyticreforming reactors and the oxygen transport membrane panels radiatingheat to the catalytic reforming reactors is from about 0.4 to about 1.0,in another embodiment from about 0.5 to about 1.0.

The present invention may also be characterized as a catalytic reformingpanel for producing synthesis gas from a hydrocarbon containing reactantfeed stream in the presence of radiant heat and steam received from aplurality of reactively driven oxygen transport membrane elements. Inthis regard, the catalytic reforming panels comprise a panel frame orsupport structure and a plurality of reforming repeating units within orattached to the panel frame or support structure and wherein thereforming repeating units are arranged in a tightly packed linear orco-planar orientation. Each reforming repeating unit contains at leastone multi-pass reforming tube in fluid communication with a feedmanifold or an exhaust manifold and each multi-pass reforming tubecontains steam reforming catalysts configured to produce the synthesisgas from the hydrocarbon containing reactant feed stream in the presenceof the radiant heat and steam. The catalytic reforming panels arepreferably placed in a juxtaposed relationship, and more preferably aparallel or substantially parallel orientation, with respect to theoxygen transport membrane elements with a view factor between the oxygentransport membrane elements radiating heat to the catalytic reformingpanels greater than or equal to about 0.4. In one embodiment, thesurface area ratio between the catalytic reforming panels and the oxygentransport membrane elements radiating heat to the catalytic reformingreactors is from about 0.5 to about 1.0.

The present invention may also be characterized as an oxygen transportmembrane array module comprising; (i) a frame or support structure; (ii)one or more oxygen transport membrane panels orientated within and/orattached to the frame, each panel comprising a plurality of oxygentransport membrane repeating units arranged in a tightly packed linearor co-planar orientation wherein each oxygen transport membranerepeating unit contains two or more oxygen transport membrane tubescoupled together at one end to form a multi-pass arrangement and theother end of the tubes configured to be in fluid communication with afirst feed manifold or a first exhaust manifold; and (iii) one or morecatalytic reforming panels orientated within and/or attached to theframe in a juxtaposed orientation with respect to the one or more theoxygen transport membrane panels, each catalytic reforming panelcomprising a plurality of reforming repeating units arranged in atightly packed linear or co-planar orientation wherein each reformingrepeating unit comprises at least one multi-pass reforming tube in fluidcommunication with a second feed manifold or a second exhaust manifold.The catalytic reforming panels are arranged in a plane parallel orsubstantially parallel to the oxygen transport membrane panels. Eachmulti-pass reforming tube contains steam reforming catalysts configuredto produce a synthesis gas from a hydrocarbon containing reactant feedstream in the presence of the radiant heat and steam produced by theoxygen transport membrane tubes.

Finally, the present invention may also be characterized as an oxygentransport membrane isolation valve assembly comprising: (i) a housingfluidically coupled to an end of an oxygen transport membrane tube, thehousing having an inlet end, an opposing discharge end, and defining aflow path therebetween wherein a portion of the housing proximate to oneof the ends is configured as a chamfered seat; (ii) a restraining pin orstructure disposed in the housing apart from the chamfered seat andprojecting into the flow path; (iii) a ceramic ball disposed in the flowpath of the housing between the chamfered seat and the restraining pinor structure and configured to rest against the restraining pin orstructure and allow gas flow through the flow path during normaloperation of the oxygen transport membrane tube and to seat against thechamfered seat and cut-off gas flow in the flow path upon a failure ofthe oxygen transport membrane.

In one embodiment of the oxygen transport membrane isolation valveassembly, the chamfered seat is disposed proximate the outlet end of thehousing and configured to cut off a feed stream to the oxygen transportmembrane. In another embodiment of the oxygen transport membraneisolation valve assembly, the chamfered seat is disposed proximate theinlet end of the housing and configured to cut off an exit path from theoxygen transport membrane and prevent backflow into the oxygen transportmembrane from the exit manifold.

Alternatively, the present invention may also be characterized an oxygentransport membrane panel for transferring radiant heat to a plurality ofsteam generating reactors or gas heating reactors, the oxygen transportmembrane panel comprising: (i) a panel frame or support structure; and(ii) a plurality of oxygen transport membrane repeating units orientatedwithin and/or attached to the panel frame and wherein the oxygentransport membrane repeating units are arranged in a tightly packedlinear or co-planar orientation. Each oxygen transport membranerepeating unit comprises two or more oxygen transport membrane tubescoupled together at one end to form a multi-pass arrangement and theother end of the tubes configured to be in fluid communication witheither a feed manifold or an exhaust manifold.

In addition, each oxygen transport membrane tube having a permeate sidelocated on an interior surface of the tube and a retentate side locatedon an exterior surface of the oxygen transport membrane tube. Theplurality of oxygen transport membrane panels are configured to separateoxygen from an oxygen containing stream contacting the retentate side ofthe oxygen transport membrane tubes in cross-flow arrangement and reactthe permeated oxygen with a gas stream containing hydrogen fuel orhydrocarbon fuel introduced into the permeate side of the oxygentransport membrane tubes thereby producing radiant heat and a reactionproduct stream. In the embodiment incorporating a plurality of steamgenerating reactors, the steam generating reactors are configured toproduce steam from a source of feed water in the presence of the radiantheat from the oxygen transport membrane panels; wherein the plurality ofsteam generating reactors comprise a feed water manifold, a steamexhaust manifold, and a plurality of steam tubes disposed in ajuxtaposed orientation with respect to the one or more the oxygentransport membrane tubes and the plurality of steam tubes in fluidcommunication with the feed water manifold and the steam collection orexhaust manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following, more detaileddescription thereof, presented in conjunction with the followingdrawings, in which:

FIGS. 1 and 2 show schematic illustrations of a synthesis gas productionsystem and underlying oxygen transport membrane technology;

FIGS. 3 and 4 show schematic illustrations of an alternate synthesis gasproduction system and underlying oxygen transport membrane technology;

FIG. 5 is a schematic illustration of an oxygen transport membranepanel;

FIGS. 6A, 6B and 7 are schematic illustrations of two configurations ofoxygen transport membrane repeating units;

FIG. 8 is a schematic illustration of a catalytic reforming panel andFIG. 9 is a schematic illustration of a catalytic reforming repeatingunit;

FIG. 10 is a schematic illustration of a dual panel module;

FIG. 11 is a schematic illustration of oxygen transport membrane panelmanifolds arrangement;

FIG. 12A is a schematic illustration of oxygen transport membraneisolation valve arrangement, while FIG. 12B is an exploded view of saidisolation valve;

FIG. 13A-C are schematic illustrations of expandable dual panel modulearrangements;

FIG. 14 is a schematic illustration of stacked dual panel modules;

FIG. 15 is a schematic illustration of an oxygen transport membranereactor pack assembly;

FIG. 16 is a schematic illustration of an alternate oxygen transportmembrane reactor pack assembly with air staging provision;

FIGS. 17 and 18 are schematic illustration of a furnace train andmultiple furnace trains, respectively;

FIG. 19 is a schematic illustration of multiple furnace arrangements ina large-scale synthesis gas production system;

FIG. 20 is a schematic illustration of an oxygen transport membranesteam generator arrangement.

DETAILED DESCRIPTION Reactively Driven Oxygen Transport Membrane BasedReforming System

Broadly speaking, the present invention may be characterized as animproved oxygen transport membrane based reforming reactor for producingsynthesis gas. The improved reactor and system provides enhanced thermalcoupling of oxygen transport membrane tubes and catalytic containingreforming tubes as well as improved manufacturability, maintainabilityand operability compared to previously disclosed oxygen transportmembrane based reforming systems and reactors.

For purposes of describing the general operation of the reactivelydriven oxygen transport membrane based reforming reactor and system,FIG. 1 and FIG. 2 show schematic illustrations of the system andunderlying oxygen transport membrane technology. As seen therein, anoxygen containing stream 110, such as air, is introduced to the system100 by means of a blower or fan 114 into a heat exchanger 113 forpurposes of preheating the oxygen containing stream 110. Heat exchanger113 is preferably a high efficiency, cyclic or continuously rotatingregenerator disposed in operative association with the oxygen containingstream 110 and the heated retentate stream 124. The heated and oxygendepleted retentate stream 124 can optionally be introduced into a ductburner region containing duct burner 126 and used to support combustionof a supplemental fuel stream 128 to produce supplemental heatintroduced into the continuously rotating regenerator 113 to preheat theoxygen containing stream 110. Alternatively, the duct burner may also bedisposed directly in the duct leaving heat exchanger 113 to pre-heat theoxygen containing stream 110. Exhaust stream 132 from heat exchanger 113is discharged.

The heated oxygen containing stream 115 is then directed via the intakeduct to the oxygen transport membrane elements 120 incorporated into theoxygen transport membrane reactor 101. Each of the oxygen transportmembrane elements 120 are preferably configured as a multilayeredceramic tube capable of conducting oxygen ions at an elevatedoperational temperature, wherein the retentate side of the oxygentransport membrane elements 120 is the exterior surface of the ceramictubes exposed to the oxygen containing stream and the permeate side isthe interior surface of the ceramic tubes. Although only six oxygentransport membrane elements 120 are illustrated in close proximity tothree catalytic reforming tubes 140, as would occur to those skilled inthe art, there could be many of such oxygen transport membrane elementsand many catalytic reforming tubes in each oxygen transport membraneassembly. Likewise, there would be multiple oxygen transport membraneassemblies used in an industrial application of the oxygen transportmembrane based reforming reactor 101.

A hydrogen containing stream is also introduced into the permeate sideof the oxygen transport membrane elements 120 and is oxidized thoughreaction with the permeated oxygen to produce a reaction product stream198 and heat. In one optional embodiment the hydrogen containing streamis a recycled portion of the produced synthesis gas 163. As a result ofseparation of oxygen and the reaction (i.e. combustion) occurring at thepermeate side of oxygen transport membrane elements 120, a heated,oxygen depleted retentate stream 124 is also formed.

As described in more detail below, the hydrogen containing stream ispreferably a portion of the heated synthesis gas stream exiting thecatalyst reforming tubes. A portion of heated synthesis gas, preferablyfrom about 25% to about 50%, is recycled to the permeate side of theoxygen transport membrane tubes 120 to react with the oxygen permeatestream to generate the heated reaction product stream and radiant heat.In one embodiment the temperature of the hot synthesis recycled gas isabove 1500° F. so as to avoid problems associated with metal dustingcorrosion.

The hot synthesis gas stream 162 is driven or pulled to the permeateside of the oxygen transport membrane tubes or elements 120 by means ofan ejector, eductor or venturi based device 199 operatively coupled tothe permeate side of the oxygen transport membrane elements 120. Bysuctioning the streams at the permeate side of the oxygen transportmembrane elements 120 into the ejector, eductor or venturi based device199 with a motive fluid comprising the pre-reformed reformer feed stream195, the reaction product stream 198 mixes with the pre-reformedreformer feed stream 195 to produce the combined feed stream 200,preferably having a steam to carbon ratio of from about 1.6 to about 3.0and a temperature of from about 1000° F. to about 1400° F. Essentially,device 199 moves the lower pressure hot synthesis gas recycle stream 162to the higher pressure combined feed stream 200.

The reaction of the hydrogen containing stream or recycled synthesis gasstream 163 at the permeate side of the oxygen transport membrane element120 produces heat. Radiation of this heat together with the convectiveheat transfer provided by heated retentate stream 124 heats thecatalytic reactor tubes 140 to supply the endothermic heatingrequirements of the steam methane reforming occurring in catalyticreactor tubes 140. As the heated retentate stream 124 exits the oxygentransport membrane based reforming reactor 101, it also heats a reformerfeed stream 138 to a temperature of from about 900° F. to about 1200° F.via indirect heat transfer using one or more coils 191 disposed in theretentate duct such that the oxygen depleted retentate stream 124 heatsthe feed streams passing through the coils 191. Also note that anysuperheated steam not added or used in the natural gas feed 182 may beexported steam 181 that can be used for power generation.

The hydrocarbon containing feed stream 182 to be reformed is preferablynatural gas. Depending on the supply pressure, the natural gas iscompressed or let down to the desired pressure via a compressor or valvearrangement (not shown) and then preheated in heat exchanger 150 thatserves as a fuel preheater. Also, since the natural gas typicallycontains unacceptably high level of sulfur species, the natural gas feedstream 182 undergoes a sulfur removal process such as hydrotreating, viadevice 190, to reduce the sulfur species to H₂S, which is subsequentlyremoved in a guard bed using material like ZnO and/or CuO. Thehydrotreating step also saturates any alkenes present in the hydrocarboncontaining feed stream. Further, since natural gas generally containshigher hydrocarbons that will break down at high temperatures to formunwanted carbon deposits that adversely impact the reforming process,the natural gas feed stream 182 is preferably pre-reformed in anadiabatic pre-reformer 192, which converts higher hydrocarbons tomethane, hydrogen, carbon monoxide, and carbon dioxide. Pre-reformersare typically catalyst-based systems. Although not shown, thispre-reformed reformer feed stream 195 may be further heated via indirectheat exchange with the heated retentate stream 124. Also contemplated,but not shown, is an embodiment where the pre-reformer may comprise aheated pre-reformer that is thermally coupled with the heated retentatestream 124 or heated oxygen containing stream 115 downstream of the ductburner.

In the illustrated system, the above-described heated reaction productstream 198 is combined with the heated pre-reformed reformer feed stream195 to produce a combined feed stream 200 that contains steam andhydrocarbons. This combined feed stream is introduced into the catalyticreactor tubes 140 where the combined feed stream 200 is subjected tosteam methane reforming to produce a synthesis gas stream 142. Thetemperature of the combined feed stream 200 is from about 1000° F. toabout 1400° F., and in another embodiment from about 1100° F. to about1400° F. Steam 180 may also be added to the combined feed stream 200,the natural gas feed stream 182, or the preheated pre-reformed reformerfeed stream 195, as required, to adjust the temperature of stream 200 aswell as the steam to carbon ratio of stream 200 to from about 1.6 toabout 3.0, and more preferably to steam to carbon ratio from about 2.0to about 2.8. The steam is preferably superheated steam 180 from about300 psia to about 1200 psia and from about 600° F. to about 1100° F. andheated by means of indirect heat exchange with the heated retentatestream 124 using steam coils 179 disposed in the retentate duct. Thesuperheated steam 180 is preferably added to the hydrocarbon containingfeed stream 182 upstream of the pre-reformer 192 to adjust the steam tocarbon ratio and final temperature of the combined feed stream 200.Also, to reduce the methane slip and optimize the economic performanceof the oxygen transport membrane based reforming reactor, the oxygentransport membrane reactor 101 should preferably be maintained at anexit pressure of less than or equal to about 250 psia, and morepreferably at an exit pressure of less than or equal to 150 psia.

The synthesis gas stream 142 produced by the oxygen transport membranebased reforming reactor 101 generally contains hydrogen, carbonmonoxide, steam and carbon dioxide other constituents such as possiblemethane slip. Heat exchange section 104 is designed to cool the producedsynthesis gas stream 142. The heat exchange section 104 is also designedsuch that in cooling the synthesis gas stream 142, various feed streamsare preheated and process steam is also generated.

The initial cooling of synthesis gas stream 142 is accomplished withsteam generation in a process gas boiler (PG boiler) 149 coupled tosteam drum 157 and designed to reduce the temperature of the cooledsynthesis gas 144 to about 760° F. or less. As illustrated in FIG. 1,the initially cooled synthesis gas stream 144 is successively furthercooled in a heat exchange network that includes hydrocarbon feedpreheater 150, economizer 156, feed water heaters 158, synthesis gascooler 161 and water cooled heat exchanger 164.

The initially cooled synthesis gas stream 144 is directed to the fuelpreheater 150 to heat the natural gas feed stream 182 and then isdirected to the economizer 156 to heat boiler feed water 188. The boilerfeed water stream 188 is preferably pumped using a feed water pump (notshown), heated in economizer 156 and sent to steam drum 157.

The cooled synthesis gas stream 146 is further cooled in a series ofsteps including a feed water heater 158, used to heat feed water stream159, followed by a synthesis gas cooler 161 and a subsequent watercooled heat exchanger 164 cooled via a separate cooling water stream166. The heated feed water 159 is directed to a de-aerator (not shown)that provides boiler feed water 188. The resulting fully cooledsynthesis gas stream 148 is then introduced into a knock-out drum 168from which a condensate stream 170 is drained to produce a fully cooledsynthesis gas stream 172. The fully cooled synthesis gas stream 172 maybe compressed in a synthesis gas compressor 174 to produce a synthesisgas product 176.

In some applications of the reactively driven oxygen transport membranebased reforming reactor and system, the produced synthesis gas shouldhave a module of from about 1.5 to about 2.2. In addition, such producedsynthesis gas stream ideally has a methane slip of less than about 4.5percent by volume where the exit pressure of the oxygen transportmembrane based reforming reactor is 250 psia or less, and morepreferably, a methane slip of less than about 2.5 percent by volumewhere the exit pressure of the oxygen transport membrane based reformingreactor is 170 psia or less.

With reference to FIGS. 3 and 4, an alternate embodiment of the oxygentransport membrane based reforming system is shown as an oxygentransport membrane based combined reforming system 401 that preferablycomprises two reactors, namely a reforming reactor and oxygen transportmembrane reactor. The reforming reactor consists of a plurality ofcatalyst containing reforming tubes 440 in which primary reforming of anatural gas feed occurs and the oxygen transport membrane reactorconsists of a plurality of catalyst containing oxygen transport membranetubes 420 where the secondary reforming occurs. FIG. 3 depicts a mock-upof the general arrangement of the two reactors and the flows associatedtherewith. FIG. 4, on the other hand, shows a schematic illustration ofthe oxygen transport membrane based combined reforming system 401.Although only six secondary reforming oxygen transport membrane tubes420 are illustrated in FIG. 3 in close proximity to three primaryreforming tubes 440, as would occur to those skilled in the art, therecould be many of such secondary reforming oxygen transport membranetubes and many primary reforming tubes in each oxygen transport membranesub-system. Likewise, there would be multiple oxygen transport membranesub-systems used in industrial applications of the oxygen transportmembrane based combined reforming system 401.

As depicted in the FIG. 3, a heated oxygen containing stream 415 isdirected via an intake duct 416 to a plurality of secondary reformingoxygen transport membrane tubes 420 incorporated into the oxygentransport membrane system 401. The secondary reforming oxygen transportmembrane tubes 420 are preferably configured as multi-layered ceramictubes capable of conducting oxygen ions at an elevated operationaltemperature, wherein the oxidant side or retentate side of the secondaryreforming oxygen transport membrane tubes 420 is the exterior surface ofthe ceramic tubes exposed to the heated oxygen containing stream 415 andthe reactant side or permeate side is the interior surface of theceramic tubes. Within each of the secondary reforming oxygen transportmembrane tubes 420 are one or more catalysts that facilitate partialoxidation and reforming of the natural gas.

A hydrocarbon containing feed stream 492, preferably natural gas, to bereformed is typically mixed with a small amount of hydrogen orhydrogen-rich gas 493 and preheated to around 370° C. in heat exchanger450 that serves as a feed pre-heater. Since natural gas typicallycontains unacceptably high level of sulfur species, a small amount ofhydrogen is typically added to facilitate desulfurization. The heatedfeed stream 482 undergoes a sulfur removal process via device 490 suchas hydro-treating to reduce the sulfur species to H₂S, which issubsequently removed in a guard bed using material like ZnO and/or CuO.The hydro-treating step also saturates any alkenes present in thehydrocarbon containing feed stream. Although not shown, the heated feedstream 482 may also undergo a pre-reforming step in, for example, anadiabatic pre-reformer which converts higher hydrocarbons to methane,hydrogen, carbon monoxide, and carbon dioxide or a heated pre-reformingstep. In the case of heated pre-reforming, it is contemplated that thecatalyst based pre-reformer be thermally coupled with the oxygentransport membrane based reforming system.

Superheated steam 480 is added to the pre-treated natural gas andhydrogen feed stream, as required, to produce a mixed feed stream 438with a steam to carbon ratio preferably between about 1.0 and 2.5, andmore preferably between about 1.2 and 2.2. The superheated steam 480 ispreferably between about 15 bar and 80 bar and between about 300° C. and600° C. and generated by means of indirect heat exchange with the heatedretentate stream 424 using steam coils 479 disposed in the retentateduct 425. Any superheated steam 480 not added or used in the natural gasand hydrogen feed 482 is exported steam 481 used for power generation.The mixed feed stream 438 is heated, by means of indirect heat exchangewith the heated retentate stream using coils 489 disposed in theretentate duct 425, to preferably between about 450° C. and 650° C., andmore preferably between about 500° C. and 600° C.

The heated mixed feed stream 438 is then sent to the reforming tubes440, which contain a reforming catalyst. The temperature of thepartially reformed hydrogen-rich synthesis gas 498 leaving the reformingtubes 440 is typically designed to be between 650° C. and 850° C. Thissynthesis gas is then fed to the oxygen transport membrane tubes 420filled with or containing a reforming catalyst. Oxygen from the heatedintake air permeates through the oxygen transport membrane tubes 420 andfacilitates reaction of a portion of the partially reformed synthesisgas 498. A portion of the energy or heat generated by this reaction isused for in-situ secondary reforming of the residual methane in thepartially reformed synthesis gas 498. The rest of the energy or heat istransferred by radiation to the reforming tubes 440 to drive the primaryreforming reactions and by convection to the oxygen-depleted stream 424.The synthesis gas 442 leaving the oxygen transport membrane tubes 420,which essentially function as a secondary reformer, is at a temperaturebetween about 900° C. and 1050° C.

The endothermic heating requirements of the reforming process occurringin the primary reforming tubes 440 is supplied through radiation of someof the heat from the secondary reforming oxygen transport membrane tubes420 together with the convective heat transfer provided by heatedretentate stream 424. In addition, as the heated, oxygen depletedretentate stream 424 exits the oxygen transport membrane based reformingsystem 401, it also heats the mixed feed stream 438 to a temperaturebetween about 450° C. and 650° C. via indirect heat transfer using oneor more coils 489 disposed in the retentate stream duct 425.

The rest of the alternate embodiment of the oxygen transport membranereforming subsystem shown in FIG. 3 is in many respects similar to theembodiment in FIG. 1. For example, an oxygen containing stream 410 isintroduced to the system by means of a forced draft (FD) fan 414 into aheat exchanger 413 for purposes of preheating the oxygen containing feedstream 410 to a temperature in the range of about 500° C. to 1050° C.

The oxygen depleted air leaves the oxygen transport membrane reformingtubes as a heated retentate stream 424 at a slightly higher temperaturethan the heated air feed stream 415. Any temperature increase, typically<50° C., is attributable to the portion of energy generated by oxidizingreaction of hydrogen and carbon monoxide in the oxygen transportmembrane tubes and transferred by convection to the air stream, offsetby the introduction of supplemental feed air, as described in moredetail below. The heated, oxygen depleted retentate stream 424 is firstused to heat the mixed feed stream to a temperature between about 450°C. and 650° C., and more preferably to a temperature between 500° C. and600° C., and may also be used to further heat steam to superheatedsteam.

The temperature of this oxygen depleted retentate stream 424 preferablyneeds to be then increased back to a temperature between about 1050° C.and 1200° C. prior to being directed to the ceramic heat exchanger orregenerator 413. This increase in temperature of the retentate stream424 is preferably accomplished by use of a duct burner 426, whichfacilitates combustion of a supplemental fuel stream 428 using some ofthe residual oxygen in the retentate stream 424. It is conceivable thatthe mixed feed heater and steam superheater could alternatively belocated in a separate fired heater (not shown). In that case, the fuelrequirements of the duct burner 426 will be substantially less. Theresulting cold retentate stream exiting the ceramic heat exchanger,typically containing less than 5% oxygen, leaves the oxygen transportmembrane based reforming system 401 system as exhaust gas 432 at atemperature of around 150° C.

Turning again to FIG. 3, the synthesis gas stream 442 produced by theoxygen transport membrane based reforming system 401 generally containshydrogen, carbon monoxide, unconverted methane, steam, carbon dioxideand other constituents. A significant portion of the sensible heat fromthe synthesis gas stream 442 can be recovered using a heat exchangesection or recovery train 404. Heat exchange section 404 is designed tocool the produced synthesis gas stream 442 exiting the oxygen transportmembrane based reforming system 401. While cooling the synthesis gasstream 442, process steam is generated, hydrocarbon feed stream ispreheated, and boiler feed water is heated.

To minimize metal dusting issues, the hot synthesis gas 442 is directlycooled to about 400° C. or less in a Process Gas (PG) Boiler 449. Theinitially cooled synthesis gas stream 444 is then used to preheat themixture of natural gas and hydrogen feed stream 482 in a fuel pre-heater450 and subsequently to pre-heat boiler feed water 488 in the economizer456 and to heat the feed water stream 459. In the illustratedembodiment, the boiler feed water stream 488 is preferably pumped usinga feed water pump (not shown), heated in economizer 456 and sent tosteam drum 457 while the heated feed water 459 is sent to a de-aerator(not shown) that provides boiler feed water 488. Synthesis gas leavingthe feedwater heater 458 is preferably around 150° C. It is cooled downto 40° C. using a fin-fan cooler 461 and a synthesis gas cooler 464 fedby cooling water 466. The cooled synthesis gas 448 then enters aknock-out drum 468 where water is removed from the bottoms as processcondensate stream 470 which, although not shown, is recycled for use asfeedwater, and the cooled synthesis gas 472 is recovered overhead.

The cooled synthesis gas stream 472 is optionally compressed in asynthesis gas compressor 474 to produce a synthesis gas product 476.Depending on the operating pressure of the oxygen transport membranebased reforming system, pressure of the recovered synthesis gas ispreferably in the range of about 10 bar and 35 bar and more preferablyin the range of 12 bar and 30 bar. The module of the synthesis gasproduced in the described embodiment is typically less than about 2.0and often less than about 1.9, whereas for some synthesis gasapplications such as methanol synthesis, the desired module of thesynthesis gas is preferably in the range of about 2.0 to 2.2. Use of anadiabatic pre-reformer upfront of the OTM reactor can increase themodule by about 0.05 to 0.1 relative to the configuration without apre-reformer. With a heated pre-reformer, it becomes possible to achievehigher modules, preferably greater than 2 and definitely greater than1.9. The exact module value depends on the operating temperature.

Oxygen Transport Membrane Elements

The oxygen transport membrane panels of the invention preferablycomprise one or more oxygen transport membrane repeating units and/orelements. In one embodiment these oxygen transport membrane repeatingunits and/or elements comprise one or more oxygen transport membranetubes that incorporate a composite structure that incorporates a denselayer, a porous support and an intermediate porous layer located betweenthe dense layer and the porous support. These tubes can be oval,substantially cylindrical, or cylindrical in structure. Each of thedense layer and the intermediate porous layer are capable of conductingoxygen ions and electrons at an elevated operational temperature toseparate the oxygen. The porous support layer would thus form thepermeate side. The dense layer and the intermediate porous layercomprise a mixture of an ionic conductive material and an electricallyconductive material to conduct oxygen ions and electrons, respectively.In one embodiment the ionic conductive material is composed of afluorite. The intermediate porous layer has a lower permeability and asmaller average pore size than the porous support layer to distributethe oxygen separated by the dense layer towards the porous supportlayer. For example, in one embodiment, the oxygen transport membraneelement is a mixed phase oxygen ion conducting dense ceramic separationlayer comprising a mixture of a zirconia based oxygen ion conductingphase and a predominantly electronic conducting perovskite phase. Thisthin, dense separation layer is implemented on a thicker inert, poroussupport.

The intermediate porous layer can have a thickness of from about 10microns to about 40 microns, a porosity of from about 25 percent toabout 40 percent and an average pore diameter of from about 0.5 micronsto about 3 microns. The dense layer can have a thickness of from about10 microns to about 30 microns. The porous surface exchange layer can beprovided with a thickness of from about 10 microns to about 40 microns,a porosity of from about 30 percent to about 60 percent and a porediameter of from about 1 micron and about 4 microns and the supportlayer can have a thickness of from about 0.5 mm to about 10.0 mm, inanother embodiment a thickness of about 0.9 mm and a pore size nogreater than 50 microns. The intermediate porous layer can contain amixture of about 60 percent by weight of(La0.825Sr0.175)0.96Cr0.76Fe0.225V0.015O3-δ, remainder 10Sc1YSZ, thedense layer can be formed of a mixture of about 40 percent by weight of(La0.825Sr0.175)0.94Cr0.72Mn0.26V0.02O3-x, remainder 10Sc1YSZ and theporous surface exchange layer can be formed by a mixture of about 50percent by weight of (La0.8Sr0.2)0.98MnO3-δ, remainder 10Sc1CeSZ.

In one embodiment the oxygen transport membrane tubes comprise one ormore catalysts. For example, catalyst particles or a solution containingprecursors of the catalyst particles can be loaded within the oxygentransport membrane tubes. Alternatively, they can be integrated in theintermediate porous layer of the oxygen transport membrane tubes, in theporous support layer adjacent to the intermediate porous layer of theoxygen transport membrane tubes and/or the interior surface of theoxygen transport membrane tubes can coated or activated with saidcatalyst.

In one embodiment the catalyst particles contain a catalyst selected topromote oxidation of the hydrogen containing stream in the presence ofthe oxygen when introduced into the pores of the porous support, on aside thereof opposite to the intermediate porous layer. The catalyst canbe gadolinium doped ceria. In another embodiment the catalyst is orcomprises a reformer catalyst. In yet another embodiment the oxygentransport membrane tubes comprise both a catalyst selected to promoteoxidation of the hydrogen containing stream in the presence of theoxygen and a reformer catalyst. Further, a porous surface exchange layercan be provided in contact with the dense layer opposite to theintermediate porous layer. In such case, the porous surface exchangelayer would form the retentate side. The support layer is preferablyformed from a fluorite, for example 3 mol % yttria stabilized zirconia,3YSZ.

Oxygen Transport Membrane Reforming Module

From the foregoing discussion, it can be readily appreciated that areactively driven oxygen transport membrane assembly or module can beconstructed or comprised of: (i) a plurality of tubular ceramic oxygentransport membranes configured to transport oxygen ions from an oxygencontaining stream present at the outside surface or retentate side ofthe tubular ceramic oxygen transport membranes to the interior surfaceor permeate side of the tubular ceramic oxygen transport membranes; (ii)a plurality of catalyst containing reformer tubes disposed adjacent orjuxtaposed relationship with the ceramic oxygen transport membrane tubesand configured to produce synthesis gas from the hydrocarbon feed in thepresence of a reforming catalyst and radiant heat generated from thetubular ceramic oxygen transport membranes; (iii) a first manifold withassociated seals to allow for a flow of a hydrocarbon feed gas and steamthrough the catalyst containing reformer tubes to produce a synthesisgas; (iv) a second manifold with associated seals to allow for the flowof a hydrogen containing gas such as synthesis gas and steam through thetubular ceramic oxygen transport membranes; (v) a recycle circuit toprovide a portion of the synthesis gas produced in the catalystcontaining reformer tubes to the tubular ceramic oxygen transportmembranes; (vi) an inlet circuit configured to provide steam and supplythe hydrocarbon feed to the assembly or module and the plurality ofcatalyst containing reformer tubes contained therein; (vii) an outletcircuit with exit manifold configured to withdraw the synthesis gasproduced in the plurality of catalyst containing reformer tubes from theassembly or module; and (viii) an air staging system configured tosupply air or other oxygen containing stream to the exterior surfaces ofthe plurality of tubular ceramic oxygen transport membranes.

When multiple oxygen transport membrane assemblies or modules arearranged within an insulated duct with a heated oxygen-containing gassuch as heated air flowing in a cross flow configuration, synthesis gaswill be produced provided the requisite steam, fuel, andhydrogen-containing gas are fed to the process side. Sufficient thermalcoupling or heat transfer between the heat-releasing ceramic oxygentransport membrane tubes and the heat-absorbing catalyst containingreformer tubes must be enabled within the design of the assemblies ormodules and the arrangement of multiple modules in an array. From about75% and 85% of the heat transfer between the ceramic oxygen transportmembrane tubes and the adjacent catalyst containing reformer tubes isthrough the radiation mode of heat transfer whereby surface area,surface view factor, surface emissivity, and non-linear temperaturedifference between the tubes, i.e. T_(otm) ⁴-T_(reformer) ⁴, arecritical elements to the thermal coupling. Surface emissivity andtemperatures are generally dictated by tube material and reactionrequirements. The surface area and radiation view factor are generallydictated by tube arrangement or configuration within each module and theentire reactor. While there are numerous tube arrangements orconfigurations that could meet the thermal coupling requirements betweenthe oxygen transport membrane tubes and the reformer tubes, a keychallenge is to achieve a relatively high production rate per unitvolume which, in turn, depends on the amount of active oxygen transportmembrane area contained within the unit volume. An additional challengeto achieving the optimum thermal coupling performance is to ascertainand optimize the size of the ceramic oxygen transport membrane tubes andthe catalyst containing reformer tubes, and more particular theeffective surface area ratio, A_(reformer)/A_(otm), of the respectivetubes. Of course, such performance optimization must be balanced againstthe manufacturability requirements, costs, as well as the reliability,maintainability, operating availability of the modules and reactor.

It has been found that significant advantages in these problem areas maybe gained by increasing the oxygen transport membrane repeating unitcapacity, reduction in catalytic reactor tube diameter, and the moduledesign and tube arrangement. With a reduction in catalytic reactor tubeoutside diameter from a range of about 2.0 to 3.0 inches found invarious prior art systems to an outside diameter range of about 0.6 to1.0 inches together with a corresponding change in tube arrangement, theamount of active oxygen transport membrane area contained within a unitvolume of reactor housing may be dramatically increased.

A preferred arrangement of oxygen transport membrane tubes 120 shown inFIG. 1 or 420 shown in FIG. 3 is a first panel arrangement 214 (FIG. 5)comprising a plurality of straight rows oxygen transport membranetubes/repeating units 204 shown in FIGS. 6A, 6B and 7 adjacent to asecond panel arrangement 216 (FIG. 8) comprising plurality of straightrows of catalyst containing reformer tubes/repeating units 208 as shownin FIG. 9. This multiple panel arrangement of oxygen transport membranetubes and catalyst containing reformer tubes improves the surface arearatio, view factor and radiative heat transfer efficiency between thedifferent tubes. Due to the improved view factor between oxygentransport membrane tubes and reforming tubes, the net tube count andoverall tube area of the reforming tubes may be reduced by a factor of30% to 40% compared to prior art designs. In addition, with a reductionin reforming tube diameter, the required wall thickness to resist creeprupture at the operating temperatures and pressures may be reducedwhich, coupled with tube count reductions results in significant costreduction.

As seen in FIG. 9, the improved oxygen transport membrane module design212 which includes a first oxygen transport membrane panel 214 and asecond reformer panel 216 allows for the significant advantagesassociated with linear row tube arrangement or co-planar tubearrangement and with reduced diameter reforming tubes. The illustratedoxygen transport membrane module design has the additional advantages ofbeing inherently modular and expandable in its approach which enablescommercial-scale applications without losing efficiency.

Oxygen Transport Membrane and Catalyst Reformer Panels

The ceramic oxygen transport membrane elements or repeating units 204utilized in one embodiment of the invention preferably comprise one ormore, in another embodiment, two or more oxygen transport membrane tubescomprised of an extruded porous cylindrical substrate which has theactive layers coated and fired on the outside cylindrical surface of thesubstrate. These tubular ceramic membrane elements are produced withhigh efficiency manufacturing process with an outside diameter in therange of about 8 mm to 20 mm and with a length/diameter ratio in therange of 50 to 75.

As shown in FIGS. 6A and 6B, a preferred coupling arrangement for anyfinal form of the ceramic tubular membrane elements is referred to as a‘hair-pin’ arrangement 204 created by adjoining two tubular membraneelements 200 together in pairs with a 180 degree elbow fitting 220 onone end. This ‘hair-pin’ arrangement represents a repeating unit of theceramic oxygen transport membrane element. An alternative preferredarrangement is another multi-pass or serpentine arrangement shown inFIG. 7 and referred to as the ‘M-pin’ arrangement. The illustrated‘M-pin’ arrangement comprises at least four (4) oxygen transportmembrane tubes or multi-tube leg segments connected in series, includingappropriate ceramic to ceramic adapters 224, and two (2) ceramic tometal adapters 228 configured to sealably connect the ends of the‘M-pin’ arrangement to form the oxygen transport membrane panel usingadvanced metal to ceramic seals. The ‘M-pin’ arrangement furtherpreferably includes a plurality of ceramic U-shaped connectorsconfigured for fluidically coupling adjacent tubes or leg segments,although a single integrated connector assembly could be used. The legsegments can be of equal lengths or different lengths. The illustratedembodiment shows the use of three (3) ceramic U-bend connectors 220 tocouple the adjacent tubes to yield the serpentine arrangement. Themulti-pass arrangement, such as the depicted ‘M-pin’ arrangement ispreferred from a manufacturability and durability standpoint

Employing the ‘hair-pin’, two-pass, M-pin or other multi-passarrangement also allows for creating higher capacity repeating units byadjoining multiple tubes together using ceramic connectors 224 to createadditional effective length of the active ceramic oxygen transportmembrane elements as shown in FIGS. 6A, 6B and 7. As discussed in moredetail below, the end opposite one of the ‘hair-pin’ ends of therepeating unit is configured to connect to the feed and exhaustmanifolds via small metal tubes 232. By placing all the membrane elementexternal connections at a single end of the module allows thermalexpansion of the module without placing additional stress on theconnections points. Since the oxygen flux along the reacting length ofthe tubular membrane element is not constant due to progressiveoxidation of the fuel gases occurring along the length of the tubularmembrane element, this two-pass arrangement in the repeating unit helpsto balance temperatures as the more reactive sections of a repeatingunit located proximate the feed is adjacent to the less reactivesections of the same repeating unit located near the exit. At the‘hair-pin’ end, the adjacent sections are both moderately reactive. Themulti-pass repeating unit is constructed by coupling tube ends through adense ceramic adapter element 224 or dense ceramic 180-degree elbowfitting 220 with glass-ceramic seals that are crystalized during themembrane element assembly firing process. The 180-degree elbow 220 is adense ceramic part generally produced through ceramic-injection moldingand joining processes.

Turning now to FIGS. 11, 12A and 12B, connecting the ends of therepeating unit to the feed and exhaust manifolds is preferablyaccomplished via small metal tubes. Transition from the end of theceramic membrane element to metal tubing at the connection end isaccomplished by joining a ceramic to metal adaptor 228 connected to themetal tubing directly to the end of the membrane element 200 or throughan intermediate dense ceramic adaptor with glass-ceramic seals. Oncetransitioned to metal tubing, the connection ‘pigtails’ 232 generallywill contain strain-relief bends as well as in-line isolation valves 236with one or more weld or braze joints facilitating the coupling. Themetal tubing at the ultimate feed or exit point of the repeating unit isconfigured to connect to the corresponding feed or exit manifold througha brazed or welded connection.

In another embodiment the invention contemplates a multi-pass oxygentransport membrane tube reactor comprising a serpentine shaped tubeassembly comprising a plurality of coupled oxygen transport membranetubes, the serpentine shaped tube assembly having a first end in fluidcommunication with a feed manifold, a second end in fluid communicationwith an exhaust manifold. The oxygen transport membrane tubes arrangedin a parallel or substantial parallel and juxtaposed orientation; andcomprise one or more isolation valve assemblies disposed between thefirst end of the tube assembly and the feed manifold or between thesecond end of the tube assembly and the exhaust manifold. Each oxygentransport membrane tube comprises a tubular porous support comprising aionically conducting structured material, in one embodiment a fluoritestructured material, a dual phase intermediate porous layer comprising amixture of an electrically conducting perovskite structured material andan ionically conducting fluorite structure material, the intermediateporous layer disposed on the porous support; and a dual phase denselayer comprising a mixture of an electrically conducting perovskitestructured material and an ionically conducting fluorite structurematerial, the intermediate porous layer disposed on the intermediateporous layer, wherein the interior surface of the porous support definesa reactive side of the oxygen transport membrane tube and the outermostsurface of the oxygen transport membrane tube defining a retentate side.

The plurality of coupled oxygen transport membrane tubes are configuredto separate oxygen from an oxygen containing stream contacting the outersurface of the oxygen transport membrane tubes through oxygen iontransport through the dense layer and intermediate porous layer to thereactive side of the oxygen transport membrane tubes at elevatedtemperatures and a difference in partial pressure of oxygen between theretentate side and the reactive side of the oxygen transport membranetubes.

The oxygen transport membrane tubes can also be configured to receive astream of a hydrogen containing stream at the reactive side from thefeed manifold and oxidize the hydrogen with the oxygen transportedthrough the layers of the oxygen transport membrane tube to produce heatdue in substantial part because of the difference in partial pressure ofoxygen between the retentate side and the reactive side of the oxygentransport membrane tubes.

The serpentine shaped tube assembly tube assembly can further compriseone or more ceramic straight connectors configured for fluidicallycoupling two oxygen transport membrane tubes in a linear arrangement andone or more ceramic U-shaped connectors configured for fluidicallycoupling two adjacent oxygen transport membrane tubes and/or one or moreceramic M-shaped connectors configured for fluidically coupling aplurality of adjacent oxygen transport membrane tubes.

The plurality of coupled oxygen transport membrane tubes are configuredto operate at a maximum allowable working pressure of 250 psia at thereactive side, in another embodiment, up to 500 psia.

In another embodiment the oxygen transport membrane tube comprises aporous surface exchange layer comprising a mixture of an electricallyconducting perovskite structured material and an ionically conductingfluorite structure material and disposed in contact with the dense layeropposite to the intermediate porous layer.

In yet another embodiment the oxygen transport membrane tube reactorcomprises a catalyst disposed within the oxygen transport membrane tube.The catalyst can be one that promotes steam reforming of the hydrogencontaining feed stream and/or one that promotes the oxidation ofhydrogen containing steam.

The isolation valves 236 are simple passive devices comprised of atubular body 240, a chamfered seat 244, a ceramic ball 248, arestraining pin 252 or feature, and the connection to the tubes ateither end (see FIGS. 12A and 12B). Alternatively, a metal or metalalloy ball can be employed instead of said ceramic ball. A singleisolation valve assembly may be used at both the entrance pigtail 256and exit pigtail 260 of the oxygen transport membrane repeating unit.The function provided by this pair of valves is to cut off the gas flowto an individual repeating unit in the case of a seal or membranebreach. On the feed side, the valve assembly is oriented at an angletypically from about 30 and 90 degrees from horizontal with therestraining pin 252 below the ceramic ball on the feed side of thevalve. In this orientation, the valve serves as an excess flow valve.The internal bore of the housing, ball diameter, ball material, andangle of the valve is selected such that in the case of a high gas flowinto the repeating element due to a seal or membrane breach, the dragforces on the ceramic ball 248 will cause it to lift and convey down thetubular housing 240 until it reaches a chamfered seat feature 244. Theincluded angle of the chamfered seat is typically 45 degrees. At thispoint, the ceramic ball 248 has a positive shut off with the seat 244and the flow to the element is effectively interrupted. In the case ofan accidental trip or actuation of this valve (start-up, transient etc.)the valve is reset by force of gravity when flow is reduced or stoppedin the feed manifold. On the return or exit connection side, the samevalve may be placed to serve as a flow check valve (see FIGS. 12A and12B). In this case, the angle of the valve is not critical (horizontalis typical) as the chamfered seat 244 is on the inlet side of thehousing and the restraining pin 252 or feature is on the exit side ofthe housing. The restraining pin 252 prevents the ceramic ball 248 fromsealing off on the exit side of the housing. In the event of a seal ormembrane breach, the reverse flow from the pressurized exit manifoldtowards the breach in the repeating unit will cause the ceramic ball toroll in the direction of reverse flow towards the chamfered seat. Onceengaged, a positive shut-off condition of the ceramic ball 248 to thechamfered seat 244 will be present and reverse flow to the repeatingunit will be interrupted. Housing materials and connections aretypically of a high temperature alloy such as Inconel 625 or Incoloy800HT and the ball material is typically alumina or zirconia ceramicmaterial as it resists sticking or bonding with the metal materials ofthe housing and seat. For the excess flow valve at 45 degreeorientation, with dense alumina ball material, the desired flow-to-closesetpoints for a range of membrane repeating unit capacities are achievedwith ball diameter to bore diameter ratios of about 0.5 to 0.9 and ballsof 0.18 inch to 0.32 inch nominal diameter.

The feed manifold 264 and exit manifold 268 are generally configured aspipe or tubing with multiple holes, ports, or sockets spaced at aprescribed distance along its length. The manifolds generally are placedside-by-side, with the ports facing in the same direction. The manifoldsare capped generally at one end and with the manifolds placedside-by-side in a generally parallel orientation. The flow is designedto enter via the feed manifold 264 through the oxygen transport membranetubes 200 and exit via the exit manifold 268 such that the bulk flow inthe manifolds is in a counter-flow arrangement. The feed 264 and exitmanifolds 268 are preferably placed into a frame 284 (FIGS. 13A-C) madeof either a metal or refractory board material. Refractory materialssuch as Duraboard™ HD from Unifrax Inc. or calcium-silicate materialfrom Zircar Inc. are preferred choices of refractory material. Metalframe material is preferred for cost and manufacturing efficiency. Caremust be taken to minimize chromium containing vapor emission from themetal alloy as well as have sufficient strength and oxidationresistance. Alumina-scale forming austenitic stainless steel such as AFAalloy is a good choice for the material as is Haynes 224.

The metal frame is preferably stamped or cut, and folded or formed, andwelded together to create a frame structure with structural railscapable of holding or retaining the plurality of oxygen transportmembrane repeating units in straight parallel rows thus forming a firstpanel assembly 214 or arrangement. The oxygen transport membranerepeating units are generally arranged horizontally within the supportframe 284 with the rail features generally engaging and retaining longrepeating unit assemblies at several points. Engagement between thesupport frame and oxygen transport membrane repeating units ispreferably at or near the junction between adjacent tubes. The preferredengagement and retention of the oxygen transport membrane repeatingunits by the frame support should allow side to side movement of thetubes along their axis so as to allow the oxygen transport membraneelements to expand and contract without additional stress.

To assemble an oxygen transport membrane panel assembly, the manifoldsare first placed into the frame support 284 on a single side and theplurality of oxygen transport membrane repeating units, already assealed sub-assemblies, are placed into the engagement or retentionfeatures in the frame support 284 with the metal tubing ends insertedinto the ports or sockets of the corresponding manifold. Theseconnections are then individually TIG welded or torch-brazed or vacuumfurnace brazed all at once in a batch process. Braze alloy is typicallynickel braze with Nicrobraze™ 210, 152, 33, 31.

In one embodiment, the plurality of OTM tubes 204 are welded to theinlet 268 and outlet manifolds 264 and the outlet manifolds are weldedto the frame members at the top and bottom of the panel. To minimizestress due to thermal expansion, the outlet manifold is welded to theframe in only one position. In one embodiment, the outlet manifold iswelded to the frame at the top of the panel (FIG. 5, frame not shown).

In another embodiment the OTM tubes 204 are supported by the frame. Onemeans of support is to rest the tubes in slots cut into the framemembers. In another embodiment the inlet 268 and outlet manifolds 264are positioned in a second plane (FIG. 11). The acute angle formedbetween this second plane of the manifolds and the plane of theplurality of OTM tubes is 45 degrees or less and such that at least oneof the manifolds is positioned at a distance of from 2 to about 5 timesthe diameter of the OTM tubes in a direction normal to the plane of theplurality of OTM tubes.

A similarly constructed second panel may be formed from catalyticreformer repeating units 208 (See FIGS. 8 and 9). In this case, thereforming tube 208 or housing is constructed using metal tubing or pipepreferably made from a suitable wrought material like Incoloy 800HT.These tubes can be oval, substantially cylindrical, or cylindrical instructure. A continuous length of 0.75 inch tubing or 0.5 NPS pipe canbe bent to form two parallel legs 206 and a 180-degree turn at one end.This two parallel leg arrangement provides a multi-pass reforming of thefeed that intensifies the reforming process while maintaining excellentthermally coupling with the adjacent radiant heat generating oxygentransport membrane tubes. As seen in the drawings, the catalyticreforming tubes are configured as a serpentine tube, or more preferablya U-shaped tube, containing steam methane reforming catalysts and thereactors are arrayed in cross-flow arrangement with the air stream. Thistwo pass flow design provides more residence time, increases surfacearea and serves to improve the radiative view factor between the oxygentransport membrane and catalytic reforming reactors.

In one embodiment, the plurality of reforming tubes 208 are welded tothe inlet manifold 272 and outlet manifold 276. The inlet manifold 272and the outlet manifold 276 are welded to the frame members at the topand bottom of the panel (FIG. 8, frame not shown). To minimize stressdue to thermal expansion, the outlet manifold is welded to the frame inonly one position. In one embodiment, that position is at the top of thepanel.

The reformer tubes 208 are supported by the frame. One means of supportis to rest the tubes in slots cut into the frame members. The inlet 272and outlet 276 manifolds of the reformer panel are positioned in a thirdplane. The acute angle formed between this third plane of the manifoldsand the plane of the plurality of reformer tubes is 45 degrees or lesssuch that at least one of the manifolds is positioned at a distance ofless than about two times the diameter of the reformer tubes in adirection normal to the plane of the plurality of reformer tubes.

The reformer tubes, if made from a nickel-chrome, or iron-nickel-chromemetal alloy with less than approximately 3% aluminum by weight willpreferably need to be coated or surface treated with a suitablealumina-based chromium barrier on all external or exposed surfaces usingselected coating materials and processes available from Hitemco,Nextech, or Praxair Surface Technologies, Inc. The catalytic reformingtubes may be filled with various metal or ceramic catalyst supportmaterials. Examples of the catalyst support materials may include foldedmetal foils, metal mesh, metal foam, or metal/ceramic pellets or otherextruded forms with an appropriate steam reforming catalysts impregnatedor wash-coated on exposed surfaces. The interior surface of thereforming tube may also be optionally coated or activated with steamreforming catalysts. End caps 209 (FIG. 9) facilitating the transitionfrom the reformer tubes to smaller diameter metal tubing pigtails 211(FIG. 9) are also preferably coated with a chromium barrier layersurface treatment and welded or brazed onto the reforming tube tocomplete the catalytic reformer repeating unit. To facilitate thewelding and/or brazing operation, the faying surfaces of the componentsto be joined can be masked to prevent alumina formation at the surfacesof the joint. Alternatively, the entire catalytic reforming tubesub-assembly can be coated with the chromium barrier surface treatmentin batch after the components are joined as long as the metal tubingconnections at the entrance and exit points have a masked surface tofacilitate joining to the manifolds. Note that there is no need orrequirement for isolation valves in line with the feed and exit ports ofthe catalytic reformer repeating unit.

In similar fashion as the ceramic oxygen transport membrane repeatingelements (OTM repeating units), the catalytic reformer repeating unitsare assembled horizontally into a suitable frame support with support orretention means provided at several points along the reformer tubelength. In this manner, the reforming tubes are free to expand andcontract without additional stresses caused by the support frame. Theend connection points for each catalyst reforming repeating units arepreferably brazed or welded to the feed and exit manifolds in similarfashion as the ceramic oxygen transport membrane repeating units werebrazed or welded to the corresponding feed and exit manifolds. With allcatalytic reformer repeating units installed in the panel formingparallel rows of reforming tubes that are welded or brazed to themanifolds, a catalytic reforming panel is completed. The total length ofeach leg in any catalytic reformer repeating unit tube preferablymatches the total length of a single leg of the oxygen transportmembrane repeating unit.

The first oxygen transport membrane panel assembly and the secondcatalytic reformer panel assembly are preferably stacked or nestedtogether to form a module, sometimes referred to as a dual panel module,with the rows of oxygen transport membrane tubes disposed juxtaposed oradjacent to the rows of catalytic reformer tubes. One or more of thesedual panel modules may be stacked together to form an array of oxygentransport membrane tubes interleaved with an array of catalytic reformertubes. This array has a characteristically high view factor between theoxygen transport membrane tubes and catalytic reformer tubes and arelatively low number of catalytic reformer tubes required to achievethermal balance. In the preferred array, there is preferably betweenabout two and four, and more preferably three or four oxygen transportmembrane tubes per catalytic reformer tube. The inlet and exit manifoldsfor the oxygen transport membrane panel and the inlet and exit manifoldsfor the catalytic reformer panel are preferably on opposite sides of thecombined panel or dual panel module when fully assembled. Thisarrangement facilitates simplified manifold connections as well as areduced thickness and tighter array for the combined panel or dual panelmodule. Although not shown, the oxygen transport membrane panels andcatalytic reformer panels may alternatively be arranged in a singlepanel module with alternating layers in lieu of the dual panelsubassembly arrangement.

In one embodiment, the frame for the first OTM panel may be integral tothe frame for the first reforming panel in that some of the frameelements are common. In one such embodiment, the inlet and outletreforming manifolds and the first reforming panel are assembled to afirst frame. Next, at least two additional frame structures are added tothe first frame, making a second frame. Finally, the inlet and outletOTM manifolds and the first OTM panel are assembled to the second frame.

Modular Oxygen Transport Membrane Based Reforming Reactor

The combination of a single oxygen transport membrane panel 214 and asingle catalytic reformer panel 216 into a dual panel module forms abasic modular unit 212 of oxygen transport membrane based reformingreactor 101 depicted in FIG. 1 or reactor 401 depicted in FIG. 3.Coupling or integrating multiple dual panel modules 212 increasesprocessing capacity and thus synthesis gas production capacity. For anyapplication of the oxygen transport membrane based reforming reactor,the exact panel size and number of dual panel modules (FIGS. 13A-C) maybe chosen to best fit the requirements. However, most practicalapplications of the oxygen transport membrane based reforming reactormay require a large number of panels. To that end, an additional levelof integration and modularization is depicted in FIG. 14, where multipledual panel modules are stacked within a refractory-lined steel containeror housing and manifolded together to form an easily installed andconnected oxygen transport membrane based reforming reactor packassembly. Advantageously, these oxygen transport membrane basedreforming reactor pack assemblies can be produced or fabricated in ashop and transported to the plant site for installation. In addition,these multiple module pack assemblies facilitate simplified handling,connecting, and servicing for plant personnel as they are easilyinstalled or removed.

As depicted in FIG. 14, one or more of the dual panel modules can bestacked together in a refractory lined housing 304 to form the core of apack assembly 300. From six and twenty dual panel modules are preferablystacked within each pack assembly. FIG. 15 is one configuration of anoxygen transport membrane reactor pack assembly containing stacked dualpanel modules 300, a dedicated section or zone 307 comprising headerarrangements to feed inlet manifolds and withdraw process streams fromoutlet manifolds of various panels. FIG. 16 is an alternateconfiguration of an oxygen transport membrane reactor pack assembly alsocontaining provision for air staging. The pack assembly housing ispreferably a carbon steel structure that provides an open window areasto allow air or other oxygen containing stream to flow across the oxygentransport membrane tubes and through the dual panel modules 212. Thehousing also has refractory lining partially surrounding the stackeddual panel modules and configured to provide thermal insulation betweenthe high temperature region containing the dual panel modules and adedicated section or zone of the pack assembly configured to contain theinlet circuit, outlet circuit and recycle circuit. The pack assemblyhousing also provides the structural support, access panels, liftpoints, etc. The multiple dual panel modules within a pack assembly aretypically manifolded together within the pack assembly in the dedicatedsection or zone 307 of the pack assembly, preferably located above or ontop of the dual panel modules. This dedicated section or zone preferablyincludes an inlet circuit configured or adapted to provide amixed-preheated-feed (e.g. natural gas and steam) to the feed manifoldsassociated with the catalyst reformer panels 216 and oxygen transportmembrane panels 214 and an outlet circuit configured or adapted toreceive and withdraw the synthesis gas produced in the catalystcontaining reformer panels 216.

The dedicated section or zone can also include a recycle circuit adaptedto provide a portion of the synthesis gas from the exit manifolds of thecatalytic reformer panels 216 to the feed manifold 264 associated withthe oxygen transport membrane panels 214. Using the recycle circuit, aportion of the synthesis gas, preferably about 25% to 50% is pulledthrough to the feed manifold of the oxygen transport membrane panels asa recycle flow. In one embodiment, each pack assembly includes one ormore gas recycle ejectors (e.g. thermo-compressors) 309 that are used tofacilitate the recycle of a portion of the synthesis gas product streamfrom the exit manifold associated with the reformer panel to the oxygentransport membrane panel feed manifold. The recycle ejectors within apack assembly use the preheated, pressurized mixed steam and natural gasfeed as the motive flow. The suction side of the recycle ejectors areattached to the exit manifold of the reformer panels such that themotive flow entrains the synthesis gas from the suction side and drivesthe gases through a converging/diverging nozzle which helps to convertmomentum energy to static pressure recovery. In general, the mixture ofnatural gas and steam motive flow and recycled synthesis gas is directedto the feed manifold of the oxygen transport membrane panels. The mixedfeed of natural gas and steam discharged from the oxygen transportmembrane panels via the exit manifold together with the reactionproducts from the oxidization of the synthesis gas in the oxygentransport membrane panels is then directed to the feed manifoldassociated with the reforming panels.

The preferred ejectors are available from Fox Venturi Products Inc. andcan produce a discharge pressure to suction pressure ratio of about1.05-1.15 on an absolute pressure basis, with a motive pressure todischarge pressure ratio of about 1.45 or above under target gascompositions and temperatures as dictated by the process conditions.Material of construction is of similar material as pack housing andpanel manifolding (e.g. Inconel 625 or Incoloy 800HT) depending onexpected service conditions. Due to the inherent process capacitythrottling available through modulation of recycle ratio, it isdesirable to have control over recycle flow rate. One preferredembodiment to effect such control is to use two or more ejectors,preferably two or three ejectors arranged in parallel on the dischargeand suction sides. The motive flow is split and separately fed to theinlet of each ejector. In an arrangement using three ejectors, theejectors are sized in a 1:2:4 relative ratios whereas in the arrangementusing two ejectors, the ejectors are sized roughly in a 1:2 relativeratio.

With this multiple ejector configuration, control is effected byselecting which combination of eductors or ejectors is receiving themotive flow. For example, in the arrangement using three ejectors oreductors, a total of seven distinct flow levels of recycle may beengaged. Similarly, a total of three distinct flow levels of recycle maybe realized in embodiments using two ejectors or eductors. Aflow-controlled mixed-feed of natural gas and steam would bypass therecycle ejectors directly to the feed manifold of reforming panels as amake-up feed to keep tight control on the oxygen/carbon ratio of thereforming process. The oxygen transport membrane based reforming reactorpack can also optionally comprise a force or pressure actuated valve,door or moveable panel to provide pressure relief for the pack assembly.

Oxygen Transport Membrane Furnace Train

As seen more clearly in FIG. 17, each oxygen transport membrane basedreforming reactor pack assembly 300 is envisioned to slide into a hotbox or furnace segment 306. Alternatively pack assemblies can be joinedtogether to form a hot box or furnace segment. These furnace segmentsmay be produced individually and connected together in series to form anoxygen transport membrane furnace train 308. Alternatively, a singlelong hot box or furnace configured to accept multiple oxygen transportmembrane based reforming reactor pack assemblies may be fabricated andshipped to the plant or constructed on site. In either embodiment, theoxygen transport membrane based reforming reactor packs are generallyinstalled in series in the oxygen transport membrane furnace train 308.Each train is configured to be connected to an air feed system 320 andretentate withdrawal system 330 (FIG. 17). Multiple oxygen transportmembrane furnace trains 308 may be arranged in parallel to form alarge-scale reformer as shown in FIGS. 18 and 19. In furnace trainarrangements comprising two or more oxygen transport membrane basedreforming reactor pack assemblies, it may be advantageous to provide anair staging system 312 to provide supplemental cooling air or trim airas well as furnace pressure relief means 316 between adjacent multipleoxygen transport membrane based reforming reactor pack assemblies in thefurnace train.

To meet capacity requirements, the size of the dual panel module 212 maybe increased in width and height and the length of the oxygen transportmembrane furnace train 308 may be increased. As shown in FIG. 13 thedual panel module 212 width can be increased by increasing the number ofceramic oxygen transport membrane repeating units 204 in the oxygentransport membrane panel 214 and increasing the effective length of thereformer repeating units 208 in the reformer panel 216. The dual panelmodule 212 height can be increased by increasing the number ofmulti-pass oxygen transport membrane repeating units 204 and reformerrepeating units 208 in the oxygen transport membrane panel 214 andreformer panel 216, respectively. The dual panel module 212 width andheight may be increased such that the internal fluid pressure dropthrough the elements of the panel does not exceed the maximum pressuredrop allowed based on the process requirements of the plant. As shown in17 the length of the train may be increased by increasing the number ofoxygen transport membrane furnace packs 300 in a train such that theretentate-side oxygen concentration does not decrease to below a minimumallowable range of 6 mole % to 15 mole % at the entrance to the lastreactor pack assembly 300 in the train 308. The preferred limit is 10mole % oxygen concentration.

Multiple furnace trains (308) may be installed to satisfy plant capacityrequirements. The preferred arrangement is to install the furnace trains(308) in parallel circuits as shown in FIGS. 18-19. Each furnace train308 contains means for fuel supply, product output, air supply,retentate output, pressure relief, and supplemental cooling air or trimair. Pressure relief devices 316 and supplemental cooling air means 312may be installed as required between adjacent reactor pack assemblies,or preferably each reactor pack assembly 300 is constructed withdedicated means for pressure relief and supplemental cooling air. Theparallel architecture allows for maintenance of one train while theremaining trains remain operating, increasing plant up-time.

The present embodiments of an oxygen transport membrane based reformingreactor provides a commercially viable method of producing synthesis gasthat has clear cost advantages and carbon footprint advantages comparedto existing SMR and/or ATR solutions.

Oxygen Transport Membrane Based Gas Heating Reactor

In another aspect, the present invention may be characterized as animproved oxygen transport membrane based steam generator or processheater or gas heating reactor for producing steam or other heatedprocess fluid or a reactor for carrying out chemical reactions. Theimproved reactor and system provides enhanced thermal coupling of oxygentransport membrane tubes and steam/fluid tubes as well as improvedmanufacturability, maintainability and operability compared topreviously disclosed oxygen transport membrane based steam generatingsystems and reactors.

Turning now to FIG. 20, there is shown a conceptual design of an oxygentransport membrane based steam generator, in which a panel array 214type arrangement of oxygen transport membranes similar to that describedabove with reference to the oxygen transport membrane based reformingreactor are used. The oxygen transport membrane steam generator isarranged in a modular fashion integrating oxygen transport membranearrays or panels 214 and separate steam generator tube arrays 380. Thearrays or panels are connected generally in a parallel orientation(although non-parallel arrangements can be employed) and can beincreased in size or quantity to accommodate larger boiler capacities.The arrays or panels are preferably housed in an insulated hot-air ductwith a common feed water drum 384 arranged in a cooler zone and a commonsteam drum 388 arranged in a separate zone. Process gas connections arearranged on one side of the reactor, making the other side accessiblefor maintenance.

The integrated packing arrangement of oxygen transport membrane tubesand steam/fluid tubes provides for efficient heat transfer, primarilythrough radiation. Alternatively, the arrangement of oxygen transportmembrane panels and adjacent heat transfer panels having a fluid passingtherethrough, can be used to provide supplemental heat to the process orin some instances a cooling source to prevent overheating of the systemor otherwise to manage the thermal load of the oxygen transport membranemodule or assembly. This concept also provides an oxygen transportmembrane based steam generator or other gas heating reactor to havesimilar advantages as the above-described oxygen transport membranebased reforming reactor with respect to packing density, modularization,low cost manufacturing, shop-fab modules, and scalability. Theintegrated packing arrangement of oxygen transport membrane tubes andsteam/fluid tubes shown in FIG. 20 can be adapted to configure oxygentransport membrane based process fluid heaters and/or reactors.

What is claimed is:
 1. An oxygen transport membrane panel fortransferring radiant heat to a plurality of catalytic reformingreactors, the oxygen transport membrane panel comprising: optionally apanel frame; and a plurality of oxygen transport membrane repeatingunits arranged in a tightly packed linear or co-planar orientation;wherein each oxygen transport membrane repeating unit comprises two ormore oxygen transport membrane tubes coupled together and configured tobe in fluid communication with either a feed manifold or an exhaustmanifold; and wherein each oxygen transport membrane tube having apermeate side located on an interior surface of the tube and a retentateside located on an exterior surface of the tube.
 2. The oxygen transportmembrane panel of claim 1 which comprises a panel frame, wherein theplurality of oxygen transport membrane repeating units are supported bysaid panel frame and are configured to separate oxygen from an oxygencontaining stream contacting the retentate side of the tubes incross-flow arrangement and react the permeated oxygen with a gas streamcontaining hydrogen and carbon containing species introduced into thepermeate side of the tubes thereby producing radiant heat and a steamcontaining reaction product stream; wherein the catalytic reformingreactors are configured to produce synthesis gas in the presence of theradiant heat and a hydrocarbon containing reactant stream optionallycontaining the reaction product stream from the oxygen transportmembrane panels; and wherein the catalytic reforming reactors arearranged in a plane substantially parallel to the oxygen transportmembrane panels.
 3. The oxygen transport membrane tube assembly of claim1 wherein the plurality of oxygen transport membrane tubes are arrangedin a juxtaposed orientation.
 4. The oxygen transport membrane tubeassembly of claim 3 wherein at least some of the plurality of oxygentransport membrane tubes are arranged in a serpentine orientation. 5.The oxygen transport membrane tube assembly of claim 1 wherein theplurality of oxygen transport membrane tubes are arranged in a generallyparallel orientation.
 6. The oxygen transport membrane tube assembly ofclaim 1 wherein the plurality of ceramic to ceramic coupling elementsfurther comprise one or more ceramic linear connectors configured forfluidically coupling two adjacent oxygen transport membrane tubes in alinear orientation.
 7. The oxygen transport membrane tube assembly ofclaim 1 wherein the plurality of ceramic to ceramic coupling elementsfurther comprise one or more ceramic U-shaped connectors configured forfluidically coupling two adjacent oxygen transport membrane tubes. 8.The oxygen transport membrane tube assembly of claim 1 wherein theplurality of ceramic to ceramic coupling elements further comprise oneor more ceramic M-shaped connectors configured for coupling three ormore oxygen transport membrane tubes.
 9. The oxygen transport membranetube assembly of claim 1 further comprising one or more isolation valveassemblies disposed between the first ceramic to metal coupling elementand the feed manifold and/or between the second ceramic to metalcoupling element and the exhaust manifold.
 10. The oxygen transportmembrane panel of claim 2 wherein the oxygen transport membranerepeating units comprises a plurality of oxygen transport membranetubes, said oxygen transport membrane tubes comprising a dense layer, aporous support and an intermediate porous layer located between thedense layer and the porous support, wherein said dense layer and theintermediate porous layer comprise a mixture of an ionic conductivematerial and an electrically conductive material, wherein said denselayer and said intermediate porous layer are effective in conductingoxygen ions and electrons.
 11. The oxygen transport membrane panel ofclaim 10 wherein the oxygen transport membrane tubes additionallycomprise a porous surface exchange layer in contact with the dense layeropposite to the intermediate porous layer.
 12. The oxygen transportmembrane panel of claim 11 wherein the porous surface exchange layer ofthe oxygen transport membrane tubes has a thickness of from about 10microns to about 40 microns, a porosity of from about 30 percent toabout 60 percent and a pore diameter of from about 1 micron to about 4microns.
 13. The oxygen transport membrane panel of 10 wherein thesupport layer of the oxygen transport membrane tubes has a thickness offrom about 0.5 mm to about 10.0 mm and a pore size 50 microns or less.14. The oxygen transport membrane panel of claim 10 wherein the poroussurface exchange layer of the oxygen transport membrane tubes forms theretentate side of the oxygen transport membrane tubes.
 15. The oxygentransport membrane panel of claim 10 wherein said ionic conductivematerial of the oxygen transport membrane tubes comprises fluorite. 16.The oxygen transport membrane panel of claim 10 wherein saidintermediate porous layer has a thickness of from about 10 microns andabout 40 microns, a porosity of from about 25 percent and about 40percent and an average pore diameter of from about 0.5 microns and about3 microns.
 17. The oxygen transport membrane panel of claim 10 whereinsaid dense layer of the oxygen transport membrane tubes has a thicknessof from about 10 microns and about 50 microns.
 18. The oxygen transportmembrane panel of claim 10 which additionally comprises a catalyst. 19.The oxygen transport membrane panel of claim 18 wherein said catalyst isloaded inside the oxygen transport membrane tubes, integrated in theintermediate porous layer of the oxygen transport membrane tubes,integrated in the porous support layer adjacent to the intermediateporous layer of the oxygen transport membrane tubes and/or the interiorsurface of the oxygen transport membrane tubes is coated or activatedwith said catalyst.
 20. The oxygen transport membrane panel of claim 19wherein the catalyst particles promote oxidation of the hydrogencontaining stream.
 21. The oxygen transport membrane panel of claim 20wherein said catalyst promoted the reforming of a hydrogen containingstream.
 22. The oxygen transport membrane panel of claim 20 wherein saidcatalyst comprises gadolinium doped ceria.
 23. The oxygen transportmembrane panel of claim 10 wherein the outside diameter of each oxygentransport membrane tube is the same or different and is in the range ofabout 8 mm to 20 mm and the length/diameter ratio in the range of 50 to150.
 24. The oxygen transport membrane panel of claim 10 whereincatalytic reforming reactor is integrated within the oxygen transportmembrane panel, and/or within a separate catalyst reforming panel. 25.The oxygen transport membrane panel of claim 10 wherein said oxygentransport membrane tubes are arranged in an M-pin arrangement.
 26. Theoxygen transport membrane panel of claim 25 wherein said M-pinarrangement comprises at least four (4) oxygen transport membrane tubesconnected in series with ceramic to ceramic seals and ceramic couplingadapters, and two (2) ceramic to metal adapters configured to besealably connect the ends of the M-pin arrangement to the feed andoutlet manifolds of an oxygen transport membrane panel.
 27. The oxygentransport membrane panel of claim 26 wherein said M-pin arrangementadditionally comprises one or more of ceramic U-shaped connectorsconfigured for fluidically coupling adjacent tubes.
 28. The oxygentransport membrane panel of claim 25 which comprising a plurality ofM-pin arrangements.
 29. An oxygen transport membrane array modulecomprising; a frame or support structure one or more oxygen transportmembrane panels supported by the frame, each panel comprising aplurality of oxygen transport membrane repeating units arranged in atightly packed linear and co-planar orientation wherein each oxygentransport membrane repeating unit contains two or more oxygen transportmembrane tubes coupled together at one end to form a multi-passarrangement and the other end of the tubes configured to be in fluidcommunication with a first feed manifold or a first exhaust manifold;and one or more catalytic reforming panels attached to the frame in ajuxtaposed orientation with respect to the one or more the oxygentransport membrane panels, each catalytic reforming panel comprising aplurality of reforming repeating units arranged in a tightly packedlinear or co-planar orientation wherein each reforming repeating unitcomprises at least one multi-pass reforming tube in fluid communicationwith a second feed manifold or a second exhaust manifold; and whereinthe catalytic reforming panels are arranged in a plane parallel to theoxygen transport membrane panels.
 30. The oxygen transport membranearray module of claim 29 wherein the catalyst reformer panel comprisesmulti-pass catalytic reforming tubes for producing synthesis gas from ahydrocarbon containing reactant feed stream in the presence of heat,wherein said multi-pass reforming tubes are in fluid communication witha feed manifold or an exhaust manifold; wherein said multi-passreforming tubes contains at least one steam reforming catalystconfigured to produce the synthesis gas from the hydrocarbon containingreactant feed stream.
 31. The oxygen transport membrane array module ofclaim 29 wherein each multi-pass reforming tube contains steam reformingcatalysts configured to produce a synthesis gas from a hydrocarboncontaining reactant feed stream in the presence of the radiant heat andsteam produced by the oxygen transport membrane tubes.
 32. The oxygentransport membrane array module of claim 30 wherein the surface arearatio between the catalytic reforming panels and the oxygen transportmembrane panels radiating heat to the catalytic reforming reactors isfrom about 0.4 to about 1.0
 33. The oxygen transport membrane arraymodule of claim 30 wherein the view factor between the oxygen transportmembrane panels radiating heat to the catalytic reforming panels isgreater than or equal to about 0.4.
 34. The oxygen transport membranearray module of claim 33 wherein said synthesis gas is produced from ahydrocarbon containing reactant feed stream in the presence of radiantheat and steam, wherein at least a part of said heat and steam isreceived from a plurality of reactively driven oxygen transport membranetubes.
 35. The oxygen transport membrane array module of claim 32wherein the multi-pass catalytic reforming tubes are constructed ofIncoloy 800HT.
 36. The oxygen transport membrane array module of claim30 wherein the catalytic reforming tubes are filled with a metal orceramic catalyst support material.
 37. The oxygen transport membranearray module of claim 36 wherein said catalyst support material is afolded metal foil, metal mesh, metal foam, extruded metal/ceramicpellets or a combination thereof, wherein said catalyst support materialis impregnated or wash-coated on exposed surfaces with at least onesteam reforming catalyst.
 38. The oxygen transport membrane array moduleof claim 36 wherein the interior surface of the reforming tubes iscoated or activated with at least one steam reforming catalyst.
 39. Anoxygen transport membrane based reforming reactor pack assemblycomprising two or more oxygen transport membrane array modules inaccordance with claim
 29. 40. The oxygen transport membrane basedreforming reactor pack assembly of claim 39 wherein said membrane arraymodules are stacked within a refractory-lined steel container or housingand manifolded together to form an oxygen transport membrane basedreforming reactor pack assembly.
 41. The oxygen transport membrane basedreforming reactor pack assembly of claim 40 wherein membrane arraymodules are manifolded together to form a pack assembly, wherein saidmodules are manifolded together in one or more dedicated zones in thepack assembly.
 42. The oxygen transport membrane based reforming reactorpack assembly of claim 41 wherein said at least one of said dedicatedzones includes an inlet circuit configured to provide amixed-preheated-feed to the feed manifolds associated with the catalystreformer panels and optionally to the oxygen transport membrane panelsand an outlet circuit configured or adapted to receive and withdraw thesynthesis gas produced in the catalyst containing reformer panels. 43.The oxygen transport membrane based reforming reactor pack assembly ofclaim 42 wherein said at least one of said dedicated zones includes arecycle circuit adapted to provide a portion of the synthesis gas fromthe exit manifolds of the catalytic reformer panels to the feed manifoldassociated with the oxygen transport membrane panels.
 44. The oxygentransport membrane based reforming reactor pack assembly of claim 43wherein a portion of the synthesis gas is drawn through to the feedmanifold of the oxygen transport membrane panels as a recycle flow. 45.The oxygen transport membrane based reforming reactor pack assembly ofclaim 44 wherein said oxygen transport membrane based reforming reactorpack assembly comprises one or more gas recycle ejectors to facilitatethe recycle of a portion of the synthesis gas product stream from theexit manifold associated with the reformer panel to the oxygen transportmembrane panel feed manifold.
 46. The oxygen transport membrane basedreforming reactor pack assembly of claim 44 which comprises an air inletand distribution system to provide supplemental cooling air to the packassembly.
 47. The oxygen transport membrane based reforming reactor packassembly of claim 44 which comprises a force or pressure actuated valve,door or moveable panel to provide pressure relief for the pack assembly.48. An oxygen transport membrane based syngas furnace train comprisingmultiple oxygen transport membrane based reforming reactor packassemblies in accordance with claim
 39. 49. The oxygen transportmembrane based syngas furnace train of claim 48 which comprises two ormore oxygen transport membrane based reforming reactor pack assembliesin series airflow through said furnace train.
 50. The oxygen transportmembrane based furnace train of claim 49 which comprises an air inletand distribution system to provide supplemental cooling air to thefurnace train.
 51. The oxygen transport membrane based furnace train ofclaim 50 comprising a force or pressure actuated valve, door, or movablepanel provides furnace pressure relief to the furnace train.
 52. Anoxygen transport membrane based syngas plant comprising a plurality ofoxygen transport membrane based furnace train units in accordance withclaim 48, wherein preheated air is supplied to each train unit, saidairflow conveyed in series through the train units, and wherein oxygendepleted air is collected from the outlet of each train unit.